This invention relates to certain azlactone copolymers. More particularly, it relates to azlactone copolymers having at least two different reactive groups and useful as intermediates for the production of a variety of useful polymeric materials.
Polymeric azlactones (also known as oxazolones) are well known and have been described in numerous patent and other publications. The functionality of pendant azlactone groups of such polymers, particularly the reaction of such groups with nucleophilic materials and without production of by-product materials, has been reported. Thus, polymerizable azlactones and their use in the production of homopolymers and copolymers having versatility in the production of useful polymeric products has been described, for example, in U.S. Pat. No. 3,488,327(issued Jan. 6, 1970 to F. Kollinsky et al.); in U.S. Pat. No. 3,583,950. (issued June 8, 1971 to F. Kollinsky et al.); in U.S. Pat. No. 4,304,705 (issued Dec. 8, 1981 to S. M. Heilmann et al.); in U.S. Pat. No. 4,737,560 (issued Apr. 12, 1988 to S. M. Heilmann et al.); by Iwakura, et al., in Journal of Polymer Science, Vol. 6, pp. 2681-2684 (1968); by L. D. Taylor, et al., in Makromol. Chem., Rapid Commun. 3, 779-782 (1982); and by J. K. Rassmussen, et al., in Encycl. Polm. Sci. Eng., Second Edition, H. F. Mark, N. Bikales, C. G. Overberger and G. Menges, Editors, Wiley, New York, N.Y., Vol. 11, pp. 558-571 (1988).
The development of reactive polymers as derivatizable materials for the attachment of various functional agents, such as catalysts, reagents, proteins, chelating agents and photographically useful groups, has been well known and is referenced, for example, in the aforementioned U.S. Pat. No. 4,737,560. Frequently, a derivatizable polymer will be especially attractive where the polymer (or intermediate polymer) can be functionalized or derivatized from an aqueous medium. It will be appreciated that various extractive methods for selective removal of metallic materials, diagnostic methods for detecting or monitoring biological substances or fluids, and other methods relying on the use of a functional agent linked to a polymeric material, will be based upon aqueous media. Where a functional agent is covalently attached to the azlactone groups of an azlactone polymer, according to the well known azlactone ring-opening reaction involving a reactive nucleophile, the attachment of the nucleophile and the functionality of the resulting derivative will be materially influenced by the affinity of the azlactone polymer for water.
Azlactone polymers in the form of homopolymers are, in general, insoluble in water and only poorly wetted by water, effectively negating the usefulness of the azlactone functionality in aqueous media. The homopolymer of 2-vinyl-4,4-dimethyl-5-oxazolone (VDMO) is, for example, soluble in organic solvents such as chloroform, dichloromethane, dimethylformamide or tetrahydrofuran, and, if kept very dry, in ethyl acetate, benzene or acetone--as reported by L. D. Taylor, et al., in Makromol. Chem. Rapid Commun. 3, 779-782 (1982). The homopolymer is, however, insoluble in water and poorly wettable. The production of an azlactone copolymer having desired hydrophilicity will be dictated for the most part by the nature of the copolymerizable monomer. In general, a suitable comonomeric material, such as an ethylenically unsaturated copolymerizable monomer, will be one having a polymerization reactivity which permits production of the desired copolymer, i.e., one which allows for production of the copolymer and not an azlactone homopolymer. In addition, the copolymerizable monomer must provide the desired hydrophilicity or contain a reactive moiety which by subsequent reaction can provide the requisite hydrophilicity. In this connection, it is to be noted that copolymerizable monomers which tend to promote hydrophilicity oftentimes contain nucleophilic moieties, such as hydroxyl or amino groups, which may tend to interfere with desired copolymerization by undesired ring-opening reaction with pendant azlactone groups. It will be appreciated that there will considerable interest in an azlactone copolymer having at least two different reactive groups and which can be used as an intermediate for the production of a variety of useful copolymeric materials, including those especially adapted to utilization in aqueous media.